The present invention relates to an electrode device for an electrochemical sensor chip and particularly to a disposable electrode device for connecting any of analytes such as chemicals and biologically derived substances exemplified by DNA, proteins, antibodies, cells, and microorganisms to the electrodes of a transducer for detecting an analyte with an enhanced sensitivity using an electrochemical method.
There are widely known in the fields of medicine, food, and environment techniques for detecting a trace amount of analyte existing in a sample with a high sensitivity. Generally, an electrochemical sensor chip comprises electrodes modified by a molecular recognition element formed of biologically derived substances, chemicals, and the like selectively reacting with an analyte in a sample. When a sample is brought into contact with these electrodes, effects produced by an interaction can be sensed by detecting a change in electric current using an electrochemical method with a high sensitivity if the sample contains a substance interacting with the molecular recognition element.
In the field of gene analyses that have made a rapid progress in recent years, trials are being made to determine DNA sequences by electrochemical methods using, for example, a technique described in JP 2573443 B. These methods enable high-sensitive analysis as to whether DNA, examined as an analyte, has a sequence that is capable of complementarily binding with probe DNA by converting one single stranded DNA obtained by denaturing the analyte DNA and another single stranded DNA having a known base sequence (probe DNA) into double-stranded DNA through hybridization, and then mixing therein an intercalated material specifically binding with double-stranded DNA and reversible with respect to redox reaction.
Electrochemical sensor chips widely use a flat electrode-type electrode device as described, for example, in JP 2007-278981 A to achieve contact with a sample. As illustrated in FIG. 15, this electrode device comprises a planar electrode 2 made of a conductive material formed on an insulation substrate 1. A sample is placed on the planar electrode 2, and the potential of the planar electrode 2 is extracted through a conductive pattern 3. The planar electrode 2 and the conductive pattern 3 can be formed by a printing method, for example, which reduces manufacturing costs so that the electrode device may be suitably used as a disposable electrode device for an electrochemical sensor chip.
JP 2003-532090 A describes another known example of electrochemical measurement, which uses an electrode formed on the surface of an integrated circuit chip. As illustrated in FIG. 16, an electrode 5 is formed on the surface of an integrated circuit chip 4, and a sample 6 is placed on the electrode 5. In this case, an additional circuit for amplifying feeble current may be integrated into the integrated circuit chip 4, so that a highly-sensitive measurement can be expected.